In general, a wind turbine or a wind turbine park is operated with the aim to obtain maximum yield of the capital invested in it, and consequently the wind turbine control systems are configured to maximize the output power, i.e. to operate the wind turbine to capture the maximal power that is available in the wind, with due regard to keeping the wind turbine within operational limits.
During operation a wind turbine experiences varying climatic conditions and the control system of the wind turbine is designed to take into account these variations. This constant adaptation to the current conditions imposes a certain and a varying level of fatigue to the wind turbine's components.
Existing wind turbines may include a monitoring system which monitors the operation and determine a number of fatigue measures of various components based on monitored signals, such as vibration signals from sensors. If a too high fatigue level is determined of a given component, the turbine may be shut down or operated in a derated mode until the component can be repaired.
The inventors of the present invention have realized that there is a need for further ways of operating a wind turbine taking fatigue exposure into account during operation of the wind turbine.